Number 01

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  • Publication
    2021-10-01Heft oder Ausgabe einer Zeitschrift
    Proceedings in Marine Biology
    (Lebenswissenschaftliche Fakultät) Dressler, Lena Elisa; Ebel, Roy; Kasper, Leonard; Raaz, Lion Vincent A.; Ehlers, Sarah; Parsi-Pour, Parima; Schaal Moreno, Guillem
    “Proceedings in Marine Biology” is an international journal publishing original research by graduate students on all aspects of marine biology. Subjects covered include: ecological surveys and population studies of oceanic, coastal and shore communities; physiology and experimental biology; taxonomy, morphology and life history of marine animals and plants. Papers are also published on techniques employed at sea for sampling, recording, capture and observation of marine organisms.
  • Publication
    2021-10-01Zeitschriftenartikel
    Beutepräferenz bei Marthasterias glacialis (Echi- nodermata, Asteroidea) in Abhängigkeit von individueller Größe und intraspezifischer Konkurrenz
    (Lebenswissenschaftliche Fakultät) Kasper, Leonard; Raaz, Lion V. A.
    Seastars are opportunistic predators that feed on bivalve molluscs and other invertebrates. In a dynamic system like the sublitoral of the rocky shores near Concarneau (South Brittany, France) there are several parameters possibly influencing the choice of prey like the tides, abundance of seastars as well as abundance of the different prey species. In two different experimental setups (five aquaria with one individual each and two aquaria with about 25 individuals each) we investigated the prey preferences of Marthasterias glacialis. We wanted to find out whether there are any prey preferences at all and if so, whether these preferences were depending on individual predator size and on intraspecific competition. The sea stars were offered 6 different prey species: Magallana gigas, Patella spec., Mytilus edulis, Phorcus lineatus, Littorina obtusata and Chthalamus spec. The results show that Mytilus edulis and Patella spec. are the most preferred prey species. In addition, our observations suggest that intraspecific competition has an influence on prey choice with a preference for organisms to be subdued and eaten in a shorter amount of time. Concluding we can say that under laboratory conditions the sea star M. glacialis shows prey preferences. Those are slightly depending on individual size and intraspecific competition. Preceding work (Gianguzza et al., 2016) supports to expect those findings to be at least in parts applicable to the natural habitat of M. glacialis.
  • Publication
    2021-10-01Zeitschriftenartikel
    Protection over mobility? How shell selection in the hermit crab Clibanarius erythropus (Paguroidea) is modulated by availability and ecological conditions.
    (Lebenswissenschaftliche Fakultät) Dressler, Lena Elisa; Ebel, Roy; Ehlers, Sarah
    Hermit crabs occupy empty gastropods shells, which have to provide both: mobility and protection. Yet, the process of shell selection and the preference for different architectural traits, such as globose or conical shapes, has not been fully understood. In this study we look into the selection behaviour of Clibanarius erythropus. Five gastropod shell types of similar size were offered in a laboratory setup. The results were compared to findings in a natural habitat in Le Cabellou, located on the French Atlantic Coast. Moreover, the radius of movement between consecutive tides was studied to infer how C. erythropus obtains shells in the absence of live gastropods. When offered in equal amounts, a vast majority selected a shell of conical shape as a final shelter, either Tritia reticulata or, to a lesser extent, Nucella lapillus. Consistent with this, these two gastropods provided the shells first selected and occupied the most time during the experiment. A similar preference for a conical shape was observed in the field. Yet, a greater fraction was found to occupy N. lapillus. Moreover, after two tides, 47 % of specimens were recovered in close vicinity to their original location. Due to this locational constancy we presume that the population depends on a passive import of certain shells. The different abundance of empty gastropod shells is likely to constitute a limiting factor that modulates shell selection under natural conditions. As a consistent result in the laboratory and the field, a clear preference for a conical shape over globose shells was identified. Although impeding mobility, this architectural trait has been discussed as providing a better protection from predation. Additionally we explain how a conical shape might be beneficial under strong hydrodynamic action, as found at Le Cabellou. Shell preference might therefore be regarded as less species-specific and more of a response to ecological conditions than previously assumed.
  • Publication
    2021-10-01Zeitschriftenartikel
    The movement radius of Patella spec. around its home scar correlates with duration of water exposure
    (Lebenswissenschaftliche Fakultät) Parsi-Pour, Parima; Schaal Moreno, Guillem
    With its extraordinary ability of orientation enabling home fidelity the limpet Patella has been of high interest for scientists during the last two centuries. To assess possible correlations between limpet behaviour and distance to the low water line it is useful to observe their active movement range from one low tide to the next low tide and also from day to night. By comparing photographs taken each day and night over the test duration we determined a degree of home fidelity of 94.2% at the rocky shores of the Breton Atlantic coast. We also observed a positive correlation between the proximity of the limpet’s home scar to the low water line and its movement radius. We present an adequate strategy as uninvasive as possible for similar studies.